Intervertebral implant with integrated fixation

ABSTRACT

A surgical instrument and method are provided for removal of a spinal implant from the intervertebral disc space. The instrument includes a carriage body for interfacing with the implant, a housing for interfacing with the vertebrae, and a handle portion having a first portion rotatably coupled with a proximal end of the housing and a second portion rotatably engageable with a proximal attachment portion of the carriage body. A central passage of the housing extends between the proximal end and a distal engagement surface of the housing. The central passage is dimensioned to mate with the carriage body. Rotation of the handle portion about an axis causes translational movement of the carriage body along the axis. A modular inserter/distractor apparatus and method and an anchor remover and method are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a national phase entry under 35 U.S.C. §371of International Application No. PCT/US2010/055259 filed Nov. 3, 2010,published in English, which claims priority from U.S. Provisional PatentApplication No. 61/257,734 filed Nov. 3, 2009, entitled IntervertebralImplant With Integrated Fixation Including An Instrument For ImplantRevision, and U.S. Provisional Patent Application No. 61/257,667 filedNov. 3, 2009, entitled Intervertebral Implant With Integrated Fixation,all of the disclosures of which are hereby incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention relates to spinal surgery. More particularly, thepresent invention relates to surgical instruments and methods of usingsuch instruments to insert and remove an implant and anchors withrespect to the intervertebral disc space and the adjacent vertebrae.

Back pain can be caused by many different things, including any one ofseveral problems that affect the intervertebral discs of the spine.These disc problems include, for instance, degeneration, bulging,herniation, thinning of a disc, and abnormal movement, and the pain thatis experienced is generally attributable to friction or pressure thatinevitably occurs when one adjacent vertebra exerts uneven pressure orwhen both adjacent vertebrae exert such pressure on the disc.Oftentimes, disc problems lead to the vertebrae impinging on one of thevery many nerves located in the spinal column.

One surgical method commonly utilized to correct such disc problems is afusion procedure where a surgeon fuses together adjacent vertebrae insingle or multiple levels. Different methods (as well as apparatus foruse in those methods) for such surgery have been developed forperformance on cervical, thoracic, or lumbar vertebral bodies. Thesefusion procedures will be referred to herein as interbody fusion or“IF.” Traditional IF techniques generally involve removing at least aportion of the troublesome disc from the patient, adding bone graftmaterial into the interbody space between the vertebrae that flank thedisc, and inserting a spinal implant device into the space to hold thegraft material in place and to support the vertebrae while solid bonemass forms therebetween. Oftentimes, the steps of inserting an implantand bone graft material involve first packing the implant with the bonegraft material, and thereafter implanting that construct.

While IF is a long-established technique for correcting theaforementioned disc problems, it is one that is constantly updated. Forinstance, different implants have been created to suit specific needs,and methods involving the insertion of such implants and the preparationof the vertebrae to receive same are constantly evolving. One majorissue that has existed and will continue to exist is the fact thatimplants inserted into the disc space often take an extended period oftime to achieve permanent fusion between the adjacent vertebrae. Thisleads to long recovery periods for the patient. Certain implants alsofail to achieve a degree of fusion that permanently eliminates flexion,extension, and axial movement between the two adjacent vertebrae. Thismay allow for the initial fusion created by the implant to wear down incertain aspects, which in turn allows for future discomfort to thepatient and potentially follow-up surgical procedures.

Thus, there exists a need for a spinal implant, method of using theimplant, and related instrumentation for such method that improves uponthese shortcomings.

BRIEF SUMMARY OF TEE INVENTION

A first aspect of the present invention is a surgical instrument forremoving a spinal implant from the intervertebral disc space between twoadjacent vertebrae, the instrument including a carriage body having adistal engagement surface for interfacing with the implant and aproximal attachment portion, a housing having a distal engagementsurface for interfacing with at least one of the adjacent vertebrae, aproximal end, and a central passage extending between the proximal endand distal engagement surface, the central passage dimensioned to matewith the carriage body, and a handle portion having a first portionrotatably coupled with the proximal end of the housing and a secondportion rotatably engageable with the proximal attachment portion of thecarriage body, wherein rotation of the handle portion about an axiscauses translational movement of the carriage body along the axis.

In accordance with certain embodiments of this first aspect, the firstportion of the handle may be rotatably coupled with the proximal end ofthe housing about one degree of rotational freedom defined by the axis.The proximal attachment portion of the carriage body may includeexterior threads and the second portion of the handle may include a borehaving internal threads that mate with the external threads. Rotation ofthe handle portion about the axis may cause relative movement betweenthe internal and external threads and translational movement of thecarriage body along the axis with respect to the housing and the handleportion. The carriage body may include a rod extending from the distalengagement surface. The rod may be threadably engageable with acorresponding aperture in the implant. The carriage body may include aknob connected with the rod for threading the rod into the aperture inthe implant. The distal engagement surface of the carriage body may becurved according to a contour of the implant. The distal engagementsurface of the housing may include first and second feet for interfacingwith the superior and inferior adjacent vertebrae, respectively. Atleast a portion of the central passage may define a first non-circulargeometry and at least a portion of an exterior surface of the carriagebody may define a second non-circular geometry dimensioned similarly tothe first non-circular geometry. The first and second geometries mayprevent relative rotation between the housing and the carriage body.

A second aspect of the present invention is a method of removing animplant from the intervertebral disc space between two adjacentvertebrae, the method including the steps of attaching a distal end of acarriage body to the implant, positioning a housing about the carriagebody such that a distal surface of the housing contacts at least one ofthe adjacent vertebrae, and rotating a handle portion rotatably coupledto a proximal end of the housing about a longitudinal axis of thehousing such that an internal thread of the handle portion interactswith an external thread on a proximal end of the carriage body, whereinthe rotating causes translational movement of the carriage body alongthe axis with respect to the housing.

In accordance with certain embodiments of this second aspect, the methodmay further include removing the implant from the disc space throughfurther rotation of the handle. The step of rotating may apply a distalforce from the distal surface of the housing onto the at least one ofthe adjacent vertebrae and a proximal force from the attached distal endof the carriage body onto the implant to remove the implant from thedisc space. The step of attaching may include securing the implant tothe distal end of the carriage body by inserting a rod of the carriagebody into an aperture of the implant. The step of inserting the rod mayinclude screwing a threaded portion of the rod into a threaded portionof the aperture. The step of screwing may include tightening thethreaded rod by way of a knob disposed on the carriage body. The step ofpositioning may include sliding an assembly of the housing and therotatably attached handle portion over the carriage body. The method mayfurther include the step of engaging the internal thread of the handleportion with the external thread of the proximal end of the carriagebody.

A third aspect of the present invention is a surgical instrument forinserting a spinal implant in the intervertebral disc space between twoadjacent vertebrae and an anchor engageable with the implant and anadjacent vertebra, the instrument including an engagement body includinga superior surface, an inferior surface, a proximal end, a distalengagement surface for interfacing with the implant, and a track on atleast one of the superior and inferior surfaces for slidably translatingthe anchor toward the engagement surface, a handle portion rotatablyconnectable to the proximal end of the engagement body, a superiordistraction rail pivotally connected at a proximal end to a superiorportion of the handle portion, and an inferior distraction railpivotally connected to at a proximal end an inferior portion of thehandle portion, wherein rotation of the handle portion about an axiscauses translational movement of the engagement body along the axis andcontact between the implant and the distraction rails forces distal endsof the rails apart from one another.

In accordance with certain embodiments of this third aspect, theinstrument may further include a trial assembly interchangeable with theengagement body, the trial assembly including a trial implant and a bodyhaving a proximal end rotatably connectable to the handle portion and adistal end for attachment to the trial implant, the trial implant havinga superior surface and an inferior surface, wherein rotation of thehandle portion about the axis causes translational movement of the trialassembly along the axis and contact between the trial implant and thedistraction rails forces the distal ends of the rails apart from oneanother. The instrument may further include a plurality of differentlysized and shaped trial implants for attachment to the body of the trialassembly, the trial implant selected from the plurality of trialimplants. The instrument may further include a rod extending from theengagement surface. The rod may be threadably engageable with acorresponding aperture in the implant. The engagement surface may becurved according to the contour of the implant. The track may beembedded within the surface. The track may include a first track on thesuperior surface and a second track on the inferior surface.

A fourth aspect of the present invention is a method of inserting animplant in the intervertebral disc space between two adjacent vertebraeand an anchor engageable with the implant and an adjacent vertebra, themethod including the steps of attaching a distal end of an engagementbody to the implant, connecting a proximal end of the engagement bodywith a handle portion such that the implant is disposed between superiorand inferior distraction rails extending distally from the handleportion, rotating the handle portion about an axis to causetranslational movement of the engagement body along the axis and contactbetween the implant and the distraction rails to force distal ends ofthe rails apart from one another, inserting the implant into the discspace by rotating the handle portion such that the implant passesdistally between the rails and into the disc space, and inserting ananchor into engagement with the implant and the adjacent vertebra.

In accordance with certain embodiments of this fourth aspect, distalends of the distraction rails may be positioned within theintervertebral disc space, and the step of rotating may actuate therails to cause distraction of the disc space. The method may furtherinclude sliding a tamp along the engagement body in contact with theanchor to force the anchor into engagement with the implant and theadjacent vertebra. The method may further include the step of cutting anentryway into the adjacent vertebra for the anchor by sliding a cutteralong the engagement body and piercing the opposing adjacent vertebra.

A fifth aspect of the present invention is a kit of surgical instrumentsfor removing a spinal implant from the intervertebral disc space betweentwo adjacent vertebrae and an anchor engaged with the implant and anadjacent vertebra, the kit including a removal tool having an engagementportion and a handle portion, the engagement portion including asuperior surface, an inferior surface, a distal engagement surface forinterfacing with the implant, and a track on at least one of thesuperior and inferior surfaces for slidably translating the anchor awayfrom the engagement surface, and an anchor remover slidably engageablewith the removal tool in contact with the anchor to pull the anchor fromengagement with the implant and the adjacent vertebra.

In accordance with certain embodiments of this fifth aspect, the kit mayinclude a cutter slidably engageable with the removal tool for piercingan adjacent vertebra to expose the anchor, the cutter having at leastone blade edge for cutting bone. The anchor remover and the cutter maybe slidably mountable within channels on the removal tool. The anchorremover and the cutter are slidably mountable within the track. Theanchor remover may include a distal end having a releasing featureextending from the distal end and configured to engage a locking tab onthe anchor to release the tab from interference with the implant. Theanchor remover may include a distal end having a grasping featureconfigured to interface with a catch on the anchor to translate proximalforces from the anchor remover to the anchor. The anchor remover mayinclude a distal end having a releasing feature and a grasping feature,the releasing feature extending from the distal end and configured toengage a locking tab on the anchor to release the tab from interferencewith the implant, and the grasping feature configured to interface witha catch on the anchor to translate proximal forces from the anchorremover to the anchor.

A sixth aspect of the present invention is a method of removing ananchor from engagement with a vertebral body and an implant disposed inthe intervertebral disc space between two adjacent vertebrae, the methodincluding the steps of engaging a distal engagement surface of a removaltool with the implant, the removal tool having superior and inferiorsurfaces and a track on at least one of the superior and inferiorsurfaces for slidably translating the anchor away from the engagementsurface, sliding an anchor remover distally along the track toward theanchor, sliding a releasing feature of the anchor remover between theimplant and a locking tab on the anchor to release the tab frominterference with the implant, interfacing a grasping feature of theanchor with a catch on the anchor to translate proximal forces from theanchor remover to the anchor, and applying a proximal force to theanchor remover to pull the anchor from engagement with the implant andthe adjacent vertebra.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of an implant and four anchors insertedinto an intervertebral disc space between two adjacent vertebrae inaccordance with an embodiment of the present invention.

FIG. 2 is a top perspective view of the implant and four anchors shownin FIG. 1.

FIG. 3 is a side elevational view of an anchor shown in FIG. 1.

FIG. 4 is a rear elevational view of the anchor shown in FIG. 3.

FIG. 4A is a top perspective view of an implant and four anchors inaccordance with another embodiment of the present invention.

FIG. 4B is a top perspective view of a jacket of the implant shown inFIG. 4A.

FIG. 4C is a top perspective view of a spacer of the implant shown inFIG. 4A.

FIG. 4D is a side elevational view of an anchor shown in FIG. 4A.

FIG. 4E is a top perspective view of the anchor shown in FIG. 4A.

FIG. 5 is a perspective view of a modular inserter/distracter apparatusassembled with a modular trial and trial implant in accordance withanother embodiment of the present invention.

FIG. 6 is a perspective view of the apparatus, modular trial, and trialimplant shown in FIG. 5 with the trial implant inserted into anintervertebral disc space.

FIG. 7 is a perspective view of the modular trial and trial implantshown in FIG. 5 with the trial implant partially inserted into theintervertebral disc space.

FIGS. 8-11 are perspective views of the apparatus shown in FIG. 5assembled with a modular inserter guide and the implant shown in FIG. 1.

FIGS. 11A-C are perspective views of a modular inserter/distracterapparatus in accordance with another embodiment of the presentinvention.

FIG. 11D-F are perspective views of a modular inserter guide inaccordance with another embodiment of the present invention.

FIG. 11G-H are perspective views of a modular trial and trial implant inaccordance with another embodiment of the present invention.

FIG. 12 is a perspective view of a cutter used in connection with themodular inserter guide shown in FIG. 8.

FIG. 13 is a perspective view of an anchor inserted in theintervertebral disc space by the modular inserter guide shown in FIG. 8and a tamp.

FIG. 14 is another top perspective view of the implant and four anchorsshown in FIG. 1 inserted into an intervertebral disc space between twoadjacent vertebrae.

FIGS. 15 and 16 are perspective views of the cutter shown in FIG. 12.

FIGS. 17 and 18 are perspective views of the tamp shown in FIG. 13.

FIGS. 19 and 20 are perspective views of an anchor remover in accordancewith another embodiment of the present invention.

FIG. 21 is a perspective view of a removal tool in accordance withanother embodiment of the present invention.

FIG. 22 is a top perspective view of a carriage body of the removal toolshown in FIG. 21.

FIG. 23 is a perspective view of the distal end of the carriage bodyshown in FIG. 21.

FIG. 24 is a top perspective view of a housing and a handle portion ofthe removal tool shown in FIG. 21.

FIG. 25 is a side sectional view of the removal tool shown in FIG. 21.

FIG. 26 is a perspective view of the removal tool shown in FIG. 21 usedin connection with an implant.

DETAILED DESCRIPTION

With reference to certain aspects of the below-described instruments,FIGS. 1-4 show an implant 170 and anchors 150, 160, 164, 166, which arealso described more thoroughly in U.S. Non-Provisional patentapplication Ser. Nos. 12/640,816, 12/640,860, and 12/640,892, thedisclosures of which are hereby incorporated by reference herein intheir entireties. In the embodiment shown, implant 170 includes, forexample, a spacer 176 and a jacket 178 disposed thereabout to provideadded strength and support for implant 170. Spacer 176 includes chambers177 a, 177 b, 177 c that can be packed with graft material. Anchor 150is essentially identical to anchors 160, 164, 166 and is configured toslidably engage implant 170 and a vertebral body adjacent theintervertebral disc space in which implant 170 is inserted. In theimplanted position, anchors 150, 164 are rigidly disposed on oppositesides of implant 170 from anchors 160, 166. Implant 170 includesinterconnection features 180, 182, 184, 186 that extend across spacer176 and jacket 178 to mate with interconnection portions 152, 162, 168,169, of anchors 150, 160, 164, 166 (best shown in FIGS. 3 and 4),respectively. Interconnection portions 152, 162, 168, 169 preferablytransmit tension, compression, shear, torsion, and bending loads betweenanchors 150, 160, 164, 166 and implant 170, so that spinal loads aredistributed from one vertebra to another through anchors 150, 160, 164,166 and across leading and trailing portions of jacket 178.

As shown, anchor 150 is generally elongate with a leading end 151 and atrailing end 153 opposite therefrom, with interconnection portion 152extending therebetween. Interconnection portion 152 is shaped and sizedto mate with interconnection feature 180 of implant 170 so as toslidably connect anchor 150 with implant 170. Anchor 150 furtherincludes a fixation portion 158 configured as a plate extending betweenleading and trailing ends 154, 156. Anchor 150 also includes legs 154,155 extending generally perpendicularly between interconnection portion152 and fixation portion 158. Leg 154, which is disposed toward leadingend 151 of anchor 150, includes a cutting edge 156 and a piercing tip157 capable of cutting through bone.

On the lower portion of interconnection portion 152 proximate trailingend 153, a locking tab 159 (best shown in FIG. 3) is biased to extendaway from interconnection portion 152. Locking tab 159 preventsmigration of anchor 150 after it is inserted, and is semi-flexible orotherwise resilient in nature so that it can flex when anchor 150 isinserted and/or removed from implant 170. Preferably, locking tab 159elastically deforms as anchor 150 is inserted into implant 170 and, oncefully inserted past the inner margin of jacket 178, springs back to aposition that creates a surface-to-surface contact with jacket 178. Thesurface-to-surface contact prevents anchor 150 from translating inanterior direction and backing out from its implanted position. Lockingtab 159 may alternatively be integrated into jacket 178 or spacer 176. Achannel feature 161 is disposed on anchor 150 to allow a removerinstrument (described below) to elastically deform the locking featureagain for removal from jacket 178. Anchor 150 also possesses a catchfeature 163 on trailing end 153 and preferably slanted toward leadingend 151 that allows it to interface with the anchor remover instrument.Catch feature 163 is configured as a lip or rim protruding from asurface of anchor 150, and allows for pulling of anchor 150 out of thevertebral body and implant 170 by an anchor remover tool, describedbelow.

A second embodiment of an implant 1170 and anchors anchors 1150, 1160,1164, 1166 are shown in FIGS. 4A-4E and are similar in nature to theabove-described embodiments. Implant 1170 includes spacer 1176 andjacket 1178. Anchor 1150, shown more clearly in FIGS. 4D and 4E,includes a locking tab 1159 and a catch feature 1163 that is morepronounced and leans in a slightly more proximal direction to facilitatea more secure engagement with a removal tool. Interconnection features1180, 1182, 1184, 1186 may include a slight recess or indent in theirperiphery to mate with a removal tool, described more fully below. Infurther embodiments, a locking tab in accordance with the presentinvention may extend from an anchor in any direction that creates anengagement with the implant, such as an inferior direction as shownabove, a medial or lateral direction, or any other direction.

In accordance with a first embodiment of the present invention, a set ofinstruments is shown in FIGS. 5-11 that are configured for installationof an implant 170 and anchors 150, 160, 164, 166. The instrumentsinclude a modular inserter/distracter apparatus 200 that facilitatesintervertebral distraction during trailing and insertion of implant 170.Apparatus 200 includes two rails 252, 254 having respective proximalends 252 a, 254 a and respective distal ends 252 b, 254 b. Rails 252,254 are pivotally connected to a handle portion 256 at proximal ends 252a, 254 a and are configured such that distal ends 252 b, 254 b may pivottowards and away from one another. Distal ends 252 b, 254 b aregenerally planar so that when in a closed position, as shown in FIG. 5,ends 252 b, 254 b can be placed within the intervertebral disc space andsubsequently forced apart to aid in distracting the space between theadjacent vertebral bodies.

Apparatus 200 is operable with both a modular trial assembly 290 (shownin FIGS. 5-7) and a modular inserter guide 201 (shown in FIGS. 8-11) tocam rails 252, 254 apart, thus creating distraction at the distal end ofapparatus 200 as a trial or permanent implant is advanced toward thedisc space. Trial assembly 290 includes a shaft 291 that can receive atits distal end a variety of trial implant in various sizes andconfigurations, such as trial implant 292. Trial implants 292 areutilized to gauge the disc space and select the most appropriatelyconfigured permanent implant 170, and can be inserted in a trailingprocedure either without apparatus 200, as shown FIG. 7, or withapparatus 200, as shown in FIGS. 5 and 6. At its proximal end, shaft 291connects with a threaded cylinder 262 that interfaces with matingthreads 258 disposed on an inner surface of handle 254. Threadedcylinder 262 can be rotatably coupled with shaft 291 such that cylinder262 may rotate about a central axis of shaft 291. In such aconfiguration, shaft 291 and trial implant 292 can maintain theirorientation with respect to rails 252, 254 while cylinder 262 is rotatedwithin handle 256.

Trial assembly 290 is preferably be assembled to apparatus 200 by firstattaching threaded cylinder 262 to the proximal end of shaft 291, andthen passing shaft 291 through a slot 270 in handle 256. Assembly 290may then be advanced distally to engage threaded cylinder 262 withthreads 258 of handle 254. A rotatable knob 260 is provided and isrotatably fixed to a proximal end of threaded cylinder 262. Turning knob260 allows threaded cylinder 262 to be translated in a proximal ordistal direction according to the orientation of the mating threads,thereby also translating trial assembly 290. Rotation of knob 260 cantherefore force trial implant 292 toward the disc space. As trialimplant 292 is moved distally, the superior and inferior faces thereofcontact rails 252, 254, respectively, and force rails 252, 254 apartfrom one another. Distal ends 252 b, 254 b of rails, which are incontact with adjacent vertebral bodies, separate from one another,thereby causing distraction of the disc space therebetween.

Once trial implant 292 is moved to a position adjacent distal ends 252b, 254 b, stops 294, 296 attached to trial implant 292 engage theadjacent vertebral bodies. Stops 294, 296 are preferably configured tohave a height that is greater than that of implant 292 such that thesuperior and inferior portions of stops 294, 296 will come into contactwith the proximal face of the vertebral bodies to prevent over insertionof trial implant 292. As stops 294, 296 encounter the vertebral body,further insertion of implant 292 is prevented, and any furthertranslation of implant 292 with respect to rails 252, 254 results inapparatus 200 moving in a proximal direction with respect to thevertebral bodies and implant 292, as shown in FIG. 6. Continued rotationof knob 260 eventually forces distal ends 252 b, 254 b out of theintervertebral disc space. Trial assembly 290 may then be disconnectedfrom apparatus 200 to further evaluate the implanted trial implant 292,which is eventually removed in favor of another process of inserting adifferently dimensioned trial implant 292 or implant 170. Of course,insertion of trial implant 292 may be interrupted at any point shouldthe size or configuration of implant 292 be deemed unacceptable withrespect to the disc space.

Modular inserter guide 201, shown in FIGS. 8-13, is similar in nature totrial assembly 290 in its cooperation with apparatus 200. Guide 201includes a shaft 240 that connects at its proximal end to threadedcylinder 262. Threaded cylinder 262 is preferably rotatably coupled withshaft 240 such that cylinder 262 may rotate about a central axis ofshaft 240. In such a configuration, shaft 240 and implant 170 canmaintain their orientation with respect to rails 252, 254 while cylinder262 is rotated within handle 256.

Modular inserter guide 201 is preferably assembled to apparatus 200 in asimilar manner as trial assembly 290, described above. As knob 260 isturned, threaded cylinder 262 is translated in a proximal or distaldirection, thereby also translating guide 201 and implant 170. Rotationof knob 260 can therefore force implant 170 toward the disc space. Asimplant 170 is moved distally, the superior and inferior faces thereofcontact rails 252, 254, respectively, and force rails 252, 254 apartfrom one another. Distal ends 252 b, 254 b of rails, which are incontact with the adjacent vertebrae, separate from one another, therebycausing distraction of the disc space.

Once implant 170 is moved to a position adjacent distal ends 252 b, 254b, stops 242, 244 attached to the implant engage the adjacent vertebralbodies, as shown more clearly in FIG. 10. Stops 242, 244 are preferablyconfigured to have a height that is greater than that of implant 170such that the superior and inferior portions of stops 242, 244 will comeinto contact with the proximal face of the vertebral bodies to preventover insertion of implant 170. As stops 242, 244 encounter the vertebralbodies, further insertion of implant 170 is prevented, and any furthertranslation of implant 170 with respect to rails 252, 254 results inapparatus 200 moving in a proximal direction with respect to thevertebral bodies and implant 170. Continued rotation of knob 260eventually forces distal ends 252 b, 254 b out of the intervertebraldisc space. Implant 170 is then in its fully implanted position, asshown in FIG. 14. As rails 252, 254 are removed from the intervertebralspace, threaded cylinder 262 disengages and apparatus 200 can be removedfrom guide 201.

Shown in FIGS. 8-11, guide 201 is capable of attaching securely toimplant 170 and placing it into the intervertebral disc space,delivering the anchors 150, 160, 164, 166, and guiding additionalinstruments, such as a tamp, cutter, and anchor remover, which are morefully described below. At a distal end 204, guide 201 includes aconcavely-curved surface 206 that is preferably shaped to match thecurvature of implant 170. Surface 206 can be planar or otherwise shapedto more accurately match the contours of the implant with which it isutilized. A threaded rod 212 extends distally of surface 206, isengageable with a threaded aperture 174 of implant 170, and may becontrolled by a rotatable knob (not shown) of guide 201 that allows theuser to tighten implant 170 to surface 206 of guide 201, thus securingimplant 170 rigidly in all six degrees of freedom with respect to guide201. Tabs 241 a, 241 b also protrude from surface 206 and engage withcorresponding portions of implant 170 to maintain the relativepositioning of implant 170 and guide 201.

Guide 201 has superior longitudinal channels 218, 219 and inferiorlongitudinal channels 220, 221 located on superior surface 228 andinferior surface 230, respectively, of guide 201 and being capable ofcontaining, aligning, and slidably delivering anchors 150, 160, 164, 166to engage with implant 170 and the adjacent vertebral bodies onceimplant 170 is inserted into the disc space. The pairs of channels 218,219, 220, 221 cross on their respective surfaces according to theorientation of the anchors 150, 160, 164, 166 with respect to implant170. Of course, channels 218, 219, 220, 221 may be oriented with respectto their respective surface 228, 230 at any angle with surface 206, andmay be crossed, angled, or parallel. Channels 218, 219, 220, 221 mayalso be angled with respect to their respective surface 228, 230 suchthat their depth extends along a direction that is perpendicular orangled or canted with their respective surface 228, 230. As shown inFIG. 11, channels 218, 219, 220, 221 are each angled with theirrespective surface 228, 230. The angles of channels 218, 219, 220, 221correspond with the orientation of the interconnection features of theimplant, and determine the final positioning of the anchors. Channels218, 219, 220, 221 are also used to guide tamp 600 when tapping therespective anchor into implant 170 and the adjacent vertebra. Tamp 600accesses channels 218, 219, 220, 221 at a proximal face 242 of distalend 204, shown more clearly in FIG. 12.

Guide 201 is preferably at least somewhat symmetrical about a horizontalplane parallel to and extending between superior and inferior surfaces228, 230 such that guide 201 may be utilized in the orientation depictedor in an inverted orientation. As implant 170 possesses a similarsymmetry, guide 201 can beneficially be connected with implant 170 ineither orientation. Guide 201 is also preferably at least somewhatsymmetrical about a vertical plane that bisects superior and inferiorsurfaces 228, 230.

Guide 201 is preferably constructed of metal, and may include two ormore metals. For example, distal end 204 may be constructed of stainlesssteel while handle shaft 240 is constructed of titanium, which may becolor anodized. Of course any other material suitable for use duringsurgery may be employed in the construction of guide 201. Preferably,the materials utilized in the construction of guide 201 are capable ofbeing sterilized multiple times, so that the inserter may be utilized inmultiple surgeries/procedures.

An alternative embodiment of apparatus 200 is shown as apparatus 1200 inFIGS. 11A-C. In this embodiment, rails 1252, 1254 are pivotally and/orflexibly connected to handle 1256, which houses knob 1260. Knob 1260includes a cylindrical extension 1261 that rotatably connects withinhandle 1254. An inner surface of extension 1261 includes internalthreads 1258 for mating with external threads disposed on a modularinserter guide. The main difference between apparatus 1200 and apparatus200 is that knob 1206 is the component having internal threads 1258, asopposed to handle 1256. Thus, apparatus 1200 is configured to interactwith a modular inserter guide or trial assembly that includes threads onits distal end.

In that respect, an alternative embodiment of guide 201 is shown asmodular inserter guide 1201 in FIGS. 11D-F. Guide 1201 is very similarto guide 201 but includes external threads 1263 on a proximal portion ofshaft 1240. Similarly, FIGS. 11G and 11E show an alternate embodiment ofmodular trial 1290 with trial implant 1292. Stops 1294, 1296 are shownconnected to trial implant 1292. A proximal portion of shaft 1291includes external threads 1265. Threads 1263 and 1265 are preferablyconfigured to interact with internal threads 1258 of apparatus 1200.

A cutter 300 is shown in FIGS. 15 and 16 and is an elongate instrumentpreferably constructed of stainless steel. Cutter 300 is primarily usedfor cutting an initial pathway through the vertebral bodies (as shown inFIG. 12), through which anchors 150, 160, 164, 166 can be led. Inparticular, cutter 300 is configured to cut a starter channel withminimal force, thereby reducing the total amount of trauma to thevertebral bodies as anchors 150, 160, 164, 166 continue to penetrate thebone. On a distal end 306, cutter 300 includes a blade surface 304.Multiple blade surfaces or needle tips may be included as necessaryaccording to the construction of the associated implant and anchors.Blade surface 304 is similar in geometry to cutting edge 156 of anchor150, minimizing the total force required to insert anchor 150. Oncemated with guide 201, cutter 300 may be impacted on a surface 308 at itsproximal end 310, such surface being disposed adjacent to and preferablyproximally of the proximal end of guide 201. Impaction of the surface atthe proximal end of cutter 300 aids in forcing blade surface 304 intothe bone.

As shown in FIGS. 17 and 18, tamp 600 is a long instrument constructedpreferably of stainless steel, and is used primarily for the insertionof anchors 150, 160, 164, 166 into the vertebral bodies (as shown inFIG. 13). Tamp 600 includes a proximal end 622 and a distal end 602 witha lead edge 604 that may or may not match the conforming geometry on theproximal end of anchor 150. When assembled to the guide 201, tamp 600engages the proximal end of anchor 150 to controllably push anchor 150into the vertebral body. The mating surfaces between tamp 600 and anchor150 can be of any configuration as long as tamp 600 may push anchor 150distally when force is exerted at proximal end 622.

Tamp 600 has a profile that allows it to fit within channels 219, 220,221, 222. Thus, sliding engagement is permitted between tamp 600 andguide 201 to control the path of tamp 600 during insertion. A stop face626 is provided that separates distal portion 606 from a main body 612.Stop face 626 is configured to abut face 242 of guide 201 during use oftamp 600 to prevent overinsertion of anchors 150, 160, 164, 166 into thevertebral bodies. Once mated with guide 201, tamp 600 may be impacted onan impaction surface 624 at proximal end 622, as shown in FIG. 17.Impaction of surface 624 aids in forcing distal end 602 of tamp 600, andaccordingly, anchors 150, 160, 164, 166 into the bone.

The method of attaching implant 170 to distal end 204 of guide 201includes inserting a threaded rod 212 into a threaded aperture 174 tosecure implant 170 to guide 201 in a particular orientation. Threadedrod 212 may be screwed into aperture 174 by the surgeon actuating aknob. Implant 170 and guide 201 are then secured to one another suchthat manipulation of guide 201 can ensure proper positioning of implantwithin the disc space.

The intervertebral disc space is prepared by removing at least a portionof the intervertebral disc material. This can be done at this stage ofthe procedure or prior to the surgeon's selection or attachment ofimplant 170. With the appropriate portion of the disc space cleared, thesurgeon aligns and inserts implant 170 into the disc space according tothe description above respecting apparatus 200. Once implant 170 isfully seated within the disc space according to the above-describedmethod, apparatus 200 may be removed so that guide 201 can be used tofacilitate the insertion of anchors 150, 160, 164, 166. To further aidin fusing implant 170 to the adjacent vertebrae, one or more of chambers177 a, 177 b, 177 c may be packed with bone graft material prior toinsertion of implant 170 within the disc space.

At this point, as shown in FIGS. 12 and 13, cutter 300 or, if tamp isprovided with the appropriate blades, tamp 600 may be used to cutentryways into the adjacent vertebrae (if so designed). These steps arenot necessary, as anchors 150, 160, 164, 166 are configured to piercethe uncut bone.

Anchor 164 is then loaded into longitudinal channel 219, which can alsobe described as a track on superior surface 228. The method of insertingan anchor according to the present invention is herein described withrespect to anchor 164, although more than one anchor may be insertedsimultaneously. Interconnection element 152 is disposed within channel219, and tamp 600 is slidably attached to guide 201 proximal of anchor164 within channel 219 as well, with least lead edge 604 in contact withthe trailing end of anchor 164. As tamp 600 is advanced toward thevertebra, it forces anchor 164 along with it and eventually into contactwith the bone. Tamp 600 is further advanced to fully insert anchor 164into the vertebra such that the interconnection element of anchor 164locks into place within interconnection feature 184 of implant 170. Stopface 626 may abut surface 242 of guide 201 during advancement to ensurethat anchor 164 is not over-inserted. Anchor 164 is eventually seatedsuch that migration and backout are prevented between anchor 164 withrespect to both implant 170 and the adjacent vertebra. Thus, axial andtorsional movement between implant 170 and the adjacent vertebra areprevented.

Anchors 150, 160, 166 may be inserted in the same manner as describedabove, although with respect to different channels of guide 201. Tamp600 may be used first on one anchor and subsequently on the others, ortwo or more tamps 600 may be utilized together. It is noted that tamp600 is generally restrained in 5 degrees of freedom with respect toguide 201 during insertion.

After tamp 600 is disengaged from guide 201, threaded rod 212 isunthreaded from implant 170 using the knob. Guide 201 is then removedfrom the surgical site, leaving implant 170 and anchors 150, 160, 164,166 in position as shown in FIG. 1. When implant 170 and anchors 150,160, 164, 166 are implanted from an anterior approach, as shown in FIG.1, the leading portion of jacket 178 is positioned in the posteriorportion of the intervertebral disc space and the trailing portion ofjacket 178 is positioned in the anterior portion of the intervertebraldisc space. In this arrangement, prosthesis implant 170 and anchors 150,160, 164, 166 may replicate the strength and stiffness of the naturalanterior and posterior longitudinal ligaments to provide superiorfixation of adjacent vertebral bodies.

In certain circumstances, one or more of anchors 150, 160, 164, 166 andimplant 170 may need to be removed from the patient. For removal of ananchor 150, 160, 164, 166, an anchor remover 400, shown in FIGS. 19 and20, may be utilized with guide 201. Remover 400 includes a proximal end402 and a distal end 404. At the distal end 404, the remover 400includes a releasing feature such as a ramp 406 that engages locking tab159 on anchor 150 such that it can be released from interference withimplant 170, and particularly, jacket 178. Also at distal end 404 is agrasping feature such as a cantilevered hook 408 that mates with aconforming feature, preferably catch 163, on anchor 150 and serves asthe pulling surface during removal. Pulling forces applied to anchorremover 400 can thusly be translated to anchor 150. Hook 408 may includea distal blade surface 410 that aids in penetrating bone. Hook 408 isseparated from the main body of remover 408 via a slot 412, which allowsfor hook 408 to move in a superior-inferior direction with someflexibility.

Anchor removal begins with guide 201 attaching onto implant 170. Thechannels 218, 219, 220, 221 of the guide 201 dictate the trajectory ofremover 400 such that it will align with anchor 150, 160, 164, 166 atthe end of each channel 218, 219, 220, 221. During anchor removal,cutter 300 may be used to penetrate the vertebral body to gain access tothe removal features of anchor 150. Such access is typically needed topenetrate the bone growth accumulated since the original surgicalprocedure during which implant 170 and anchors 150, 160, 164, 166 wereinserted. Once guide 201 is attached to implant 170, remover 400 can beslid distally along the appropriate channel of guide 201 to reach anchor150. Hook 408 is forced toward trailing end 153 of implant 170. As itapproaches, ramp 406 slides between the implant and the inferior-mostsurface of locking tab 159 to move tab 159 in a superior direction andrelease it from interference with implant 170. Hook 408 is forcedfurther and to a point where angled surface 414 contacts catch 163. Hook408 is allowed to flex upward until a hook edge 416 drops down overcatch 163. In such a position, hook edge 416 and catch 163 are engagedsuch that a proximal force on remover 400 will be transferred to anchor150. A proximal force may then be applied to remover 400 by any knownmeans, including a slide weight or other hammer-like mechanism. Anchor150 is pulled proximally from the vertebra and along the correspondingchannel of guide 201 and removed.

In another embodiment shown in FIGS. 21-26, a removal tool 700 isprovided for removing implant 170, with or without attached anchors,from the intervertebral disc space. Tool 700 is preferably utilized withan implant alone, or else with an implant configured with anchors alongaxes parallel with the proximal-distal axis of implant 170. Anchors thatare angled with respect to the proximal-distal axis, such as those withrespect to implant 170 above, make removal of the implant and engagedanchors more difficult and such removal may cause additional trauma tothe patient. The function of removal tool 700 is to extract the implantwith minimal trauma to the patient.

As shown in FIG. 21, Removal tool 700 includes a carriage body 710, ahousing 740, and a handle portion 770. Carriage body 710, shown moreclearly in FIGS. 22 and 23, includes a distal engagement surface 712 forinterfacing with implant 170, a proximal attachment portion 714, and abody 716 extending therebetween. Distal engagement surface 712 may becurved according to a contour of implant 170. A rod 718 extends fromdistal engagement surface 712 and may have threads for engaging with athreaded aperture in the implant, such as aperture 174. A knob 720 isconnected with rod 718 for threading rod 718 into aperture 174. Rod 718is preferably disposed in body 716. An additional post 719 may extendfrom distal engagement surface 712 for additional engagement with acorresponding feature of implant 170. Proximal attachment portion 714 ofcarriage body 710 includes a shaft 722 extending from body 716 and acylindrical portion 724 extending from shaft 722 and having exteriorthreads 726. Additionally, carriage body 710 may include markings toassist the surgeon in determining the proper positioning of carriagebody 710 relative to implant 170 and/or the disc space.

Shown in FIGS. 24 and 25, housing 740 is tubular in shape and includes adistal engagement surface 742 for interfacing with at least one of theadjacent vertebrae, a proximal end 744, and a central passage 746extending therebetween. Central passage 746 is dimensioned to slidablymate with the exterior surface of carriage body 710. Distal engagementsurface 742 of housing 740 preferably includes first and second feet748, 750 for interfacing with the superior and inferior adjacentvertebrae, respectively. Feet 748, 750 include relatively large flatsurfaces capable of contacting the bony regions of the spine withoutdoing damage to the vertebral body itself or subsiding into the bone.The distal portion of housing 740 is generally rectangular in geometry,while the proximal end is generally circular in cross-section. Theproximal circular section forms a cylindrical tube portion with featuresthat are capable of interfacing with handle portion 770.

Handle portion 770, shown in FIGS. 24 and 25, includes a first portion772 rotatably coupled with proximal end 744 of housing 740 and a secondportion 774 rotatably engageable with proximal attachment portion 714 ofcarriage body 710. First portion 772 is rotatably coupled with proximalend 744 about one degree of rotational freedom defined by a generallylongitudinal axis extending along the length of housing 740, while theother two degrees of rotational freedom and the three translationaldegrees of freedom between handle portion 770 and housing 740 areconstrained. The rotatable connection between housing 740 and handleportion 770 is preferably an overlapping or interference fit, such thatno translational movement is caused between housing 740 and handleportion 770 when one is rotated with respect to the other. Theconnection between housing 740 and handle portion 770 preferably causesthem to be joined as a housing/handle assembly 790.

Second portion 774 of the handle includes a bore 776 having internalthreads 778 that mate with external threads 726 of carriage body 710.Rotation of handle portion 770 about the longitudinal axis of housing740 causes relative movement between the internal and external threads778, 726 (when such are engaged) and, thus, translational movement ofcarriage body 710 along the axis with respect to housing 740 and handleportion 770. Handle portion 770 also includes a grip 780 to be graspedby the surgeon to actuate handle portion 770.

Central passage 746 of housing 740 is dimensioned so that carriage body710 can slide therein. Preferably, at least a portion of central passage746 defines a non-circular geometry that mates with a similarnon-circular geometry of at least a portion of an exterior surface ofcarriage body 710. In this way, the mating geometries form a track forcarriage body 710 to ride on when carriage body 710 and housing 740 areinterfaced. In this configuration, when handle portion 770 is rotatedwith respect to housing 740, no similar rotation will occur betweencarriage body 710 and housing 740. Thus, rotation of handle portion 770will simply cause translational movement of carriage body 710 withrespect to housing 740. The non-circular geometries can take on anyshape so that relative rotation between housing 740 and carriage body710 is prevented, such as rectangular, oval, etc.

A method of using removal tool 700 includes first attaching distalengagement surface 712 of carriage body 710 to implant 170 while theimplant is implanted in the intervertebral space between two vertebrae.Housing/handle assembly 790 is then positioned over carriage body 710such that distal engagement surface 742 of the housing contacts at leastone of the adjacent vertebrae. Feet 748 and 750 are preferablyconfigured to each contact a surface of a vertebral body, as shown inFIG. 26.

Internal threads 778 of handle portion 770 are engaged with externalthreads 726 of carriage body 710. Handle portion 770 is rotated withrespect to proximal end 744 of housing 740 such that internal threads778 of handle portion 770 interact with external threads 726 of carriagebody 710. Such rotation of handle portion 770 causes cylindrical body724 to translate the axis of housing 740, and thus, causes movement ofcarriage body 710 and implant 170. The effect of such rotation on theseated implant 170 forces feet 748 and 750 into engagement with thevertebral bodies. Once no further distal movement of housing 740 canoccur with respect to the vertebral bodies, further rotation of handleportion 770 causes implant 170 to pull out of the disk space. A distalforce from distal engagement surface 742 of housing 740 onto theadjacent vertebrae and a proximal force from the attached distalengagement surface 712 of carriage body 710 onto implant 170 thereforeact to remove implant 170 from the disc space. Housing 740 is configuredto accept any anchors attached to implant 170 into central passage 746during removal of implant 170, as shown in FIG. 26. Thus, tool 770 isprovided to remove implant 170 through a lead screw mechanism thatcauses removal of implant 170 via a torque provided by a surgeon. Tool770 is capable of removing implant 170 without the need to hammer orimpact an instrument, thus reducing the trauma to the patient.

In alternative embodiments, tool 700 may be configured to include animpaction or slight weight device in lieu of the screw mechanism. Insuch an embodiment, a surgeon may hammer on a surface of the tool toremove the implant from the disc space. In another alternativeembodiment, the screw mechanism may be replaced with a lever arm and camarrangement, in which an eccentric cam may be mechanically attached to arelatively long thin lever arm that can be grasped by the surgeon. Whenthe lever arm is pulled, the cam rotates causing the implant to beremoved from the disc space.

The instruments according to the present invention are preferablyconstructed of metal, although other types of materials may be used thatgive the proper strength to the instruments. Such materials could behard polymeric materials or other plastics. Of course any other materialsuitable for use during surgery may be employed in the construction ofany of the instruments. Preferably, the materials utilized are capableof being sterilized multiple times, so that the instruments may beutilized in multiple surgeries/procedures.

The above-described devices and methods may be utilized in any interbodyfusion procedure, such as ALIF (Anterior Lumbar Interbody Fusion), PLIF(Posterior Lumbar Interbody Fusion), TLIF (Transforaminal LumbarInterbody Fusion), and lateral interbody fusion approaches. The modulartrials and modular inserter guides may be used alone, without themodular inserter/distracter, to insert trials and implants into the discspace.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

INDUSTRIAL APPLICABILITY

The present invention enjoys wide industrial applicability including,but not limited to, systems and methods including surgical instrumentsfor implantation and removal of intervertebral implants.

The invention claimed is:
 1. A surgical instrument for removing a spinalimplant from the intervertebral disc space between two adjacentvertebrae, the instrument comprising: a carriage body having a distalengagement surface for interfacing with the implant and a proximalattachment portion; a housing having a distal engagement surface forinterfacing with a proximally facing surface of at least one of theadjacent vertebrae when removing the spinal implant, a proximal end, anda central passage extending between the proximal end and distalengagement surface, the central passage dimensioned to mate with thecarriage body; and a handle portion having a first portion and a secondportion, the first portion being rotatably coupled with the proximal endof the housing about one degree of rotational freedom defined by theaxis, and the second portion being rotatably engageable with theproximal attachment portion of the carriage body; wherein rotation ofthe handle portion about an axis causes translational movement of thecarriage body along the axis.
 2. The instrument of claim 1, wherein theproximal attachment portion of the carriage body includes exteriorthreads and the second portion of the handle includes a bore havinginternal threads that mate with the external threads.
 3. The instrumentof claim 2, wherein rotation of the handle portion about the axis causesrelative movement between the internal and external threads andtranslational movement of the carriage body along the axis with respectto the housing and the handle portion.
 4. The instrument of claim 1,wherein the distal engagement surface of the carriage body is curvedaccording to a contour of the implant.
 5. The instrument of claim 1,wherein the distal engagement surface of the housing includes first andsecond feet for interfacing with the superior and inferior adjacentvertebrae, respectively.
 6. A surgical instrument for removing a spinalimplant from the intervertebral disc space between two adjacentvertebrae, the instrument comprising: a carriage body having a distalengagement surface for interfacing with the implant and a proximalattachment portion; a housing having a distal engagement surface forinterfacing with a proximally facing surface of at least one of theadjacent vertebrae when removing the spinal implant, a proximal end, anda central passage extending between the proximal end and distalengagement surface, the central passage dimensioned to mate with thecarriage body; and a handle portion having a first portion rotatablycoupled with the proximal end of the housing and a second portionrotatably engageable with the proximal attachment portion of thecarriage body; wherein rotation of the handle portion about an axiscauses translational movement of the carriage body along the axiswherein the carriage body includes a rod extending from the distalengagement surface, the rod being threadably engageable with acorresponding aperture in the implant.
 7. The instrument of claim 6,wherein the carriage body includes a knob connected with the rod forthreading the rod into the aperture in the implant.
 8. A surgicalinstrument for removing a spinal implant from the intervertebral discspace between two adjacent vertebrae, the instrument comprising: acarriage body having a distal engagement surface for interfacing withthe implant and a proximal attachment portion; a housing having a distalengagement surface for interfacing with a proximally facing surface ofat least one of the adjacent vertebrae when removing the spinal implant,a proximal end, and a central passage extending between the proximal endand distal engagement surface, the central passage dimensioned to matewith the carriage body; and a handle portion having a first portionrotatably coupled with the proximal end of the housing and a secondportion rotatably engageable with the proximal attachment portion of thecarriage body; wherein rotation of the handle portion about an axiscauses translational movement of the carriage body along the axis, andwherein at least a portion of the central passage defines a firstnon-circular geometry and at least a portion of an exterior surface ofthe carriage body defines a second non-circular geometry dimensionedsimilarly to the first non-circular geometry.
 9. The instrument of claim8, wherein the first and second geometries prevent relative rotationbetween the housing and the carriage body.
 10. A method of removing animplant from the intervertebral disc space between two adjacentvertebrae, the method comprising the steps of: attaching a distal end ofa carriage body to the implant; positioning a housing about the carriagebody such that a distal surface of the housing contacts at least one ofthe adjacent vertebrae; and rotating a handle portion rotatably coupledto a proximal end of the housing about a longitudinal axis of thehousing such that an internal thread of the handle portion interactswith an external thread on a proximal end of the carriage body, whereinthe rotating causes translational movement of the carriage body alongthe axis with respect to the housing.
 11. The method of claim 10,further comprising removing the implant from the disc space throughfurther rotation of the handle.
 12. The method of claim 11, wherein thestep of rotating applies a distal force from the distal surface of thehousing onto the at least one of the adjacent vertebrae and a proximalforce from the attached distal end of the carriage body onto the implantto remove the implant from the disc space.
 13. The method of claim 10,wherein the step of attaching includes securing the implant to thedistal end of the carriage body by inserting a rod of the carriage bodyinto an aperture of the implant.
 14. The method of claim 13, wherein thestep of inserting the rod includes screwing a threaded portion of therod into a threaded portion of the aperture.
 15. The method of claim 14,wherein the step of screwing includes tightening the threaded rod by wayof a knob disposed on the carriage body.
 16. The method of claim 10,wherein the step of positioning includes sliding an assembly of thehousing and the rotatably attached handle portion over the carriagebody.
 17. The method of claim 16, further comprising the step ofengaging the internal thread of the handle portion with the externalthread of the proximal end of the carriage body.